Cochran is part of the Republican establishment disparaged by the Club for Growth, the Senate Conservatives Fund, and tea party activists, as too willing to cooperate with Democrats, insufficiently conservative, and lacking zeal to rein in federal spending.

Former Gov. Haley Barbour, who left office in 2012, is a pivotal figure in Mississippi politics who, together with nephews Henry and Austin Barbour, operate a political machine that sees itself as defending tradition in the face of a sly interloper backed by opportunistic outsiders, according to Politico.

Cochran, 76, is seeking a seventh term. He is described in the Almanac of American Politics as conservative though not rigid, and as an amiable patrician who has consistently delivered federal largesse to his state.

The vast Barbour political and donor network is heavily committed to Cochran's victory over McDaniel. Austin Barbour helps set political strategy for Cochran while Henry Barbour helps raise campaign funds. All the Barbours are accomplished lobbyists working across state lines and inside the Washington Beltway.

The elder Barbour, 66, said that he and Cochran have "worked together for Mississippi for 40 years" and that he "got involved helping Thad when I was a law student," Politico reported.

Cochran said Barbour's skill as a D.C. lobbyist has been a boon to the state. "He built the nation's No. 1 lobbying firm, representing businesses that employ millions of Americans and helping fund universities and hospitals in Mississippi."

McDaniel, 41, said that the Barbours are disconnected from average Mississippians.

"Haley's talented. He's intelligent, he's shrewd. His nephews are talented and intelligent and shrewd." But McDaniel, who is also a state senator, continued, "the conservative movement is bigger than one family. It represents the will of the people."

Barbour counters: "I am sure these outside groups that are funding the McDaniel campaign would like to make the campaign about anything but Thad Cochran's record and his ability to be effective for Mississippi for the next six years."

He credits Cochran as being instrumental in bringing disaster relief funds to the state after Hurricane Katrina through his role on the Senate Appropriations Committee.